Portable, self-contained data collection systems and methods

ABSTRACT

A portable self-contained data collection system for measuring and collecting vibration data from machines includes an accelerometer coupled to the analog input of a data acquisition card that samples and digitizes the analog signal to produce a time domain digital signal. The data acquisition card output is coupled to a battery-powered portable computer that includes a database having machine identifications and associated measurement parameters. The portable computer processes the time domain digital signal according to the measurement parameters associated with a selected machine identification, and produces a frequency domain digital signal by performing a Fast Fourier Transform and other digital signal processing operations. The frequency domain signal is also analyzed in the portable computer to produce predictive maintenance information. A power supply for supplying power to the accelerometer is also included.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of prior application Ser. No.09/152,429, filed on Sep. 14, 1998, now U.S. Pat. 6,411,921, which is acontinuation of prior application Ser. No. 08/526,981, filed on Sep. 12,1995, now U.S. Pat. 5,808,903.

FIELD OF THE INVENTION

This invention relates to predictive maintenance systems and methods,and more particularly to computer-based data collection systems andmethods for measuring and collecting vibration data from machines.

BACKGROUND OF THE INVENTION

Data collection systems and methods are now widely used for measuringand collecting vibration data from machines, for predictive maintenancepurposes. Data collection systems typically include two majorcomponents: a portable data collector and a host computer. The portabledata collector is typically a dedicated instrument to whichaccelerometers can be coupled, and which stores accelerometer-basedvibration data for a machine. An example of a state-of-the-art datacollector is the EMONITOR® dataline™ data collector marketed by EntekScientific Corporation, assignee of the present application. TheEMONITOR® dataline™ data collector is described in a manual entitled“EMONITOR® for Windows EMONITOR® dataline™ (U.S.) Data Collector User'sGuide, First Edition 1995”, Manual No. EEW2501A, published by EntekScientific Corporation, the disclosure of which is incorporated hereinby reference.

The host computer is typically a standard PC-based computer which runspredictive maintenance data management and analysis software thereon.The host software allows a user to set up a database to model themachinery for which vibration data is to be obtained. The softwareallows lists of machines to be set up for data collection. Each listincludes a set of measurement parameters that control where and how totake and store a measurement. The host software allows one or more liststo be loaded into the data collector for collection. The user then takesthe data collector to a machine to be measured, accesses the measurementparameters for that machine, and collects and stores vibration and otherinformation. After collection, the data is unloaded from the datacollector to the host. The host software then allows the data to beanalyzed. Reports can be generated, including reports of measurementsthat exceed alarms. Graphical displays of the data can be produced,including trend, spectrum, frequency trend, time waveform and spectrummap plots.

An example of data management and analysis host software is EMONITOR®for Windows, which is marketed by Entek Scientific Corporation, theassignee of the present invention. The EMONITOR® for Windows software isdescribed in a manual entitled “EMONITOR® for Windows User's Guide,Second Edition 1994”, Manual No. EEW0002B, published by Entek ScientificCorporation, the disclosure of which is incorporated herein byreference.

In state-of-the-art manufacturing environments, the capital investmentin machinery can be staggering. Accordingly, there is a great need forpredictive maintenance to prevent machine breakdowns and increasereliability. Moreover, with “just in time” manufacturing requirements,predictive maintenance becomes even more critical to eliminate machinedown time. Accordingly, there is a great need for data collectionsystems and methods.

Unfortunately, the high cost of data collection systems is often abarrier to their widespread use. The high cost is in part related to theuse of special purpose hardware and software in the data collector. Inaddition to high cost, the use of special purpose hardware and softwarelimits the flexibility of the data collector and makes it difficult toupdate and improve the data collector. Although portable computers,laptop computers, pen-based computers, palmtop computers and PersonalDigital Assistants (PDA) have become widely available, they have not yetmade a significant impact on data collectors. See for example, thepublication in Automatic ID News, April 1995, entitled “Be Ready forTechnology Leap at the End of the Century: Three Non-ADC Developments toSpringboard Automatic Data Capture Growth”. See also the publication inMaintenance, January/February 1995, by Billson et al. entitled “PortablePen Computers—An Essential Tool for the Mobile Maintenance Engineer”.

SUMMARY OF THE INVENTION

The present invention is a portable, self-contained data collectionsystem for measuring and collecting vibration data from machines. Thesystem includes an accelerometer including a motion sensitive transducerand an accelerometer output. The accelerometer is coupled to a machineto produce an analog signal at the accelerometer output. The system alsoincludes a data acquisition card having an analog input and a digitaloutput. The accelerometer output is electrically coupled to the analoginput. As used herein, electrical coupling includes wireless, optical orconventional wire coupling. The data acquisition card samples anddigitizes the analog signal to produce a time domain digital signal,i.e. a sampled and digitized series of voltage versus time points, atthe digital output. The system also includes a battery-powered portablecomputer such as a pen-based computer, which includes an expansion slot.The data acquisition card digital output is electrically andmechanically connected to the expansion slot.

The battery-powered portable computer also includes a database havingmachine identifications and associated measurement parameters. Userinput means such as a pen allows user selection of a machineidentification for measurement. The portable computer also includessignal processing means for processing the time domain digital signalaccording to the measurement parameters associated with the selectedmachine identification. Preferably, the signal processing meansprocesses the time domain digital signal to produce a frequency domaindigital signal by performing a Fast Fourier Transform (FFT), wavelet orother digital signal processing operations. Finally, the battery-poweredportable computer also preferably includes signal analyzing means foranalyzing the frequency domain digital signal to produce predictivemaintenance information such as spectral distribution. The time domaindigital signal can also be analyzed to produce crest factor and otherpredictive maintenance information.

A data collection system according to the present invention uses astandard portable computer such as a pen-based computer and a standarddata acquisition card such as a PCMCIA sound card, to provide portableself-contained hardware for data collection and analysis. The machinedatabase, signal processing means and signal analyzing means arepreferably implemented using software modules which execute on theportable computer. The machine database and the signal analyzingsoftware may be provided using EMONITOR® for Windows or other predictivemaintenance software on the portable computer. Signal processingsoftware may be provided by conventional digital signal processingsoftware which provides digital filtering, integration from accelerationto velocity or displacement units, Fast Fourier Transform or othermathematical functions, and averaging. Accordingly, a low costself-contained data collection system is provided.

It will be understood that since the portable data collection systemincludes a database, signal processing software and signal analyzingsoftware therein, a host computer connection is not required foroperation. Rather, all predictive maintenance operations may beperformed using only the portable self-contained data collection system.However, it will also be understood by those having skill in the artthat the portable self-contained data collection system can be used aspart of a networked data collection system wherein the portable computerincludes transmitting means for transmitting at least one of the machineidentifications, the measurement parameters, the time domain digitalsignal, the frequency domain digital signal or the predictivemaintenance information to a second computer. The second computer maystore this data for distribution to other users and the second computeror other users may also perform one or more of the processing functionsof the portable data collector. The transmitting means is preferablywireless, such as a radio frequency (RF) transmitter. However,transmission may also be accomplished by uploading information toanother computer using conventional wire communications.

According to another aspect of the present invention, the portableself-contained data collection system also includes a power supply forsupplying power to the accelerometer. In particular, conventionalportable computers do not provide sufficient power for an accelerometer,which typically requires 24V at 2 mA. According to the invention, anaccelerometer power supply electrically and mechanically couples theaccelerometer output to the data acquisition card analog input. Theaccelerometer power supply is preferably responsive to the dataacquisition card for supplying power to the accelerometer when the dataacquisition card is activated, and for deactivating when the dataacquisition card is deactivated.

In particular, the accelerometer power supply includes a power supplyhousing and an accelerometer battery power supply in the power supplyhousing which provides sufficient power for an accelerometer. Outputmeans including an output connector electrically and mechanicallyconnects the accelerometer battery power supply to an accelerometer andreceives accelerometer signals from the accelerometer. Input meansincluding an input connector electrically and mechanically connects theaccelerometer battery power supply to an external device, preferably theanalog input of a data acquisition card. The input means receives acontrol signal from the external device, and also passes theaccelerometer signals to the external device. The accelerometer batterypower supply is responsive to the control signal, to activate theaccelerometer battery power supply to supply battery power for anaccelerometer to the output connector. In the absence of the controlsignal, the accelerometer battery power supply is deactivated.Preferably, the accelerometer battery power supply will pass signalsfrom the output means to the external device in the absence of thecontrol signal, so that non-powered transducers can be used.

When the accelerometer power supply is included, the portableself-contained data collection system includes three hardwarecomponents: a portable computer, a data acquisition card and anaccelerometer power supply. The portable computer includes a portablecomputer housing, a portable computer battery power supply within theportable computer housing to supply power to the portable computer, andan expansion slot in the portable computer housing. The data acquisitioncard is mechanically and electrically coupled to the expansion slot. Theaccelerometer power supply includes a power supply housing, and anaccelerometer battery power supply within the power supply housing whichprovides sufficient power for an accelerometer. The accelerometer powersupply is electrically and mechanically coupled to the data acquisitioncard and the accelerometer is electrically and mechanically coupled tothe accelerometer power supply. The portable computer, data acquisitioncard and accelerometer power supply may be packaged in a ruggedizedcarrying case. The portable computer executes software including adatabase including machine identifications and measurement parameters,signal processing software for processing accelerometer signals andsignal analyzing software for analyzing the processed signal to producepredictive maintenance information.

Data collection methods according to the present invention are used formeasuring and collecting vibration data from machines, wherein thefollowing steps are all performed in a portable battery-poweredcomputer: A machine identification for measurement is selected. A timedomain accelerometer signal is processed according to measurementparameters associated with the selected machine identification toproduce a digital signal. The digital signal is analyzed to producepredictive maintenance information. If necessary, the processing step ispreceded by the step of sampling and digitizing an analog accelerometersignal to produce the time domain accelerometer signal. The machineidentifications, measurements, time domain signal, digital signal and/orpredictive maintenance information can be displayed on the portablebattery-powered computer. Portable self-contained data collectionsystems and methods are thereby provided. In addition, this informationcan be transferred to another computer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a data collection system for collecting vibrationdata from machines according to the present invention.

FIG. 2 is a block diagram illustrating a data acquisition cardinterfaced to an operating system, database, signal processing means andsignal analyzing means implemented in a battery operated portablecomputer according to the present invention.

FIG. 3 is a block diagram illustrating signal processing means,including filtering, integration, fast Fourier transform, and averaging,for processing a time domain digital signal according to the presentinvention.

FIG. 4 is a block diagram illustrating a power supply for anaccelerometer according to the present invention.

FIGS. 5a, 5 b, 5 c, 5 d and 5 e illustrate data collection operationsaccording to the present invention.

FIGS. 6a-6 c are computer screen images illustrating a machineidentification selection according to the present invention.

FIG. 7 is a computer screen image illustrating signal analyzingaccording to the present invention.

FIG. 8 is a diagram illustrating a data collection system implemented ina battery operated portable computer linked to other computers in acomputer network according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring now to FIG. 1, data collection system 100 is illustrated,housed in a case 101. As shown, data collection system 100 includes abattery-powered portable computer 110 mating to data acquisition card120, display means 130, user input means 140, power supply 150, andaccelerometer 160.

The construction of battery powered portable computer 110 is well-knownto those skilled in the art. Battery operated portable computerstypically include a microprocessor, associated random access memory(RAM), nonvolatile data storage such as a hard disk drive, a batterypower source and expansion slots designed to accommodate circuit boardselectrically coupling the computer components to external devices suchas keyboards, pens, mouses, transducers and displays. These expansionslots typically accommodate standard form factor circuit cards, such asthe industry-standard PCMCIA form factor cards used in notebook andlaptop computers. For field uses, such as monitoring of machinery forpredictive maintenance purposes, battery operated portable computer 110may be mounted in a lightweight, rugged hand-held case 101, and userinput means 140 may include a magnetic pen designed to operate with amagnetically sensitive screen matrix. An example of a typical batteryoperated portable computer designed especially for field use is theFujitsu Stylistic 500, as described in Fujitsu brochure 58-0349-00B, thedisclosure of which is incorporated herein by reference. This computeris referred to for purposes of explanation only, and it will beunderstood by those skilled in the art that the present invention may beused with other portable computers.

Data acquisition card 120 is an analog to digital (A/D) converter cardthat mechanically and electrically couples data acquisition card 120 toan expansion slot in battery powered portable computer 110, electricallyconnecting digital output 122 to battery operated portable computer 110.Data acquisition card 120 is electrically coupled to accelerometer 160at analog input 121. Typically, data acquisition card 120 is a low-coststandard form factor sound card designed to receive audio frequencyanalog signals at analog input 121. An example of such a sound card isthe Magic Ram PCMCIA 16-bit audio adapter, which is described in amanufacturer's data sheet entitled “PCMCIA 16-bit Audio Adapter,” thedisclosure of which is incorporated herein by reference. This device isa standard PCMCIA form factor card that mates with a PCMCIA expansionslot. It will be understood by those skilled in the art that a dataacquisition card according to the present invention includes any A/Dconverter card capable of receiving analog inputs and transmittingcorresponding digital signals to a battery operated portable computerthrough a digital communications port, such as an expansion slot. Itwill also be understood by those skilled in the art that the presentinvention may be used with a battery operated portable computer 110which includes an analog input and associated internal A/D.

Accelerometer 160 produces an analog signal corresponding to theaccelerations experienced by a motion sensitive transducer includedtherein, and is electrically coupled to data acquisition card 120 byanalog input 121. The motion-sensitive transducer is typicallypiezoelectric and produces a voltage proportional to the acceleration ofthe transducer. The accelerometer includes means for coupling the motionsensitive transducer to a machine from which the user desires vibrationdata, such as a probe extension, screw or magnet attached to theaccelerometer structure. Examples of piezoelectric accelerometers may befound in Catalog QSG-200, published by Industrial MonitoringInstrumentation Division of PCB Piezotronics, Inc., the disclosure ofwhich is incorporated herein by reference. It will be understood bythose skilled in the art that the present invention may be used withother measurement devices producing analog output signals correspondingto accelerations, such as piezotransistor or variable resistanceaccelerometers.

Power supply 150 supplies electrical power to accelerometer 160,receives output signals from accelerometer 160, receives control signalsfrom data acquisition card 120, and conveys output signals fromaccelerometer 160 to data acquisition card 120. Power supply 150 ismechanically and electrically coupled to both accelerometer 160 and dataacquisition card 120.

Referring now to FIG. 2, a block diagram illustrates accelerometer 160,data acquisition card 120 and user input means 140 interfaced to anoperating system 200, data collection interface 210, database 220,signal processing means 230 and signal analyzing means 240. Operatingsystem 210 is typically executive software that controls data collectioninterface 210, database 220, signal processing means 230, signalanalyzing means 240, and data acquisition card 120, responsive tocommands received through user input means 140. Such commands may be toacquire or store data, or to perform filtering, time domain analysis, orfrequency domain analysis. An example of operating system 200 is EntekScientific Corporation's EMONITOR® for Windows data management software,as described in “EMONITOR® for Windows User's Guide, Second Edition1994,” Manual No. EEW0002B, the disclosure of which is incorporatedherein by reference. This software is a Windows-based program thatenables a user to perform database manipulation, data analysis or otheroperations via manipulation of screen icons. It will be understood bythose skilled in the art that the present invention may be used, forexample, with other operating systems running in a Windows, DOS, or UNIXenvironment.

Database 220 comprises a plurality of machine identifications andassociated measurement parameters. Database 220 may have a hierarchical,relational or other structure and is typically organized according tological relationships between particular machines. An example of ahierarchical database structure is incorporated in Entek ScientificCorporation's EMONITOR® for Windows, as described in Chapters 4 and 5 of“EMONITOR® for Windows User's Guide, Second Edition 1994,” Manual No.EEW0002D. This database is a SQL database that organizes machineidentifications, and associates parameters such as machine location,signal processing parameters and previously measured data values withthese machine identifications. This database is referred to for purposesof explanation, and it will be understood by those skilled in the artthat the present invention may be used with other hierarchical ornon-hierarchical database structures, and may include variouscombinations of machine parameters.

Data collection interface 210 is preferably a software module thatcontrols the operation of data acquisition card 120 and signalprocessing means 230 through operating system 200, although hardware orsoftware/hardware combinations may be employed. Upon commands from datacollection interface 210, data acquisition card 120 samples anddigitizes an analog signal 115 received from a accelerometer 160 andprovides a corresponding time domain digital signal 125, which isconveyed to signal processing means 230. In the embodiment of thepresent invention shown in FIG. 2, data collection interface 210 is asoftware module operating in conjunction with, for example, an operatingsystem such as EMONITOR® for Windows running in a Windows environment,and is conveniently accessed and controlled by user selection ofappropriate icons in a display window.

Although the combination of elements described in FIG. 2 envisions datacollection, database management and data analysis integrated in amultitasking environment such as Windows, it will be understood by thoseskilled in the art that the present invention may be practiced usingother means of interfacing data acquisition card 120, signal processingmeans 230, signal analyzing means 240 and database 220. For example,data collection interface 210 may be a standalone software programcapable of transferring data from data acquisition card 120 to database220 for subsequent data management, signal processing and signalanalysis. In another arrangement, data acquisition card 120 may includeall or a portion of signal processing means 230, allowing sampling,digitizing and processing of analog signal 115 to be performed on dataacquisition card 120. An example of such an integrated PCMCIA card isthe Bullet_(dsp) card marketed by Communication Automation and Control,Inc. The Bullet_(dsp) card is described in a data sheet entitled “PCMCIATI TMS320C32,” published by Communication Automation and Control, Inc.,the disclosure of which is incorporated herein by reference.

Signal processing means 230 performs digital signal processing of timedomain digital signal 125 received from data acquisition card 120.Typically, signal processing means 230 is implemented in conventionalmodular software blocks, which may be selected and combined to performvarious processing functions, as further illustrated in FIG. 3. Thissoftware may implement functions such as filtering, fast Fouriertransform, integration or averaging, which may be selected and arrangedas desired.

Signal analyzing means 240 typically is software that examines processeddigital signals received from signal processing means 230 and producespredictive maintenance information. Upon commands received throughoperating system 200, signal analyzing means 240 conducts analyses suchas trend analysis, alarm detection, spectral analysis, data plotting orreport generation. An example of signal analyzing means 240 is theanalysis software incorporated in Entek Scientific Corporation'sEMONITOR® for Windows, as described in Chapters 7, 9, 10 and 11 of“EMONITOR® for Windows User's Guide, Second Edition 1994,” Manual No.EEW0002B.

Referring now to FIG. 3, a software block diagram illustrates signalprocessing software for implementing signal processing means 230 whichincludes modular processing elements 310 a-310 d which may be selectedand combined as required. It will be understood by those skilled in theart that other arrangements of signal processing elements may be usedwith the present invention. In addition, it will be understood by thoseskilled in the art that other non-modular signal processing softwaretechniques may be used with the present invention.

Referring now to FIG. 4, an electrical block diagram illustrates powersupply 150 for accelerometer 160. Power supply housing 410 enclosesaccelerometer battery power supply 420. Accelerometer battery powersupply 420 provides sufficient power to excite an externalaccelerometer. Output means 430 electrically and mechanically couplesaccelerometer battery power supply 420 to an external accelerometer.Typically, output means 430 will include an MS-3106 connector commonlyused in accelerometer applications, but it will be understood by thoseskilled in the art that other structures may be used with the presentinvention, including coaxial and other types of standard connectors.

Input means 440 electrically and mechanically couples accelerometerbattery power supply 420 to an external device, such as an A/Dconverter, and receives control signal 450 from the external device.Accelerometer battery power supply 420 may be responsive to controlsignal 450, deactivating power output to the external accelerometer inthe absence of control signal 450, thus offering the capability tominimize power consumption during non-measurement periods and extendingbattery life or time between recharges.

FIG. 4 shows accelerometer battery power supply 420 further includingbattery 422, charging means 424, and regulating means 426. Chargingmeans 424 provides the capability to charge battery 422. Regulatingmeans 426 takes the power output from battery 422 and provides thevoltage and current conditioning required to excite the externalaccelerometer. It will be understood by those skilled in the art thatnot all of these elements are required for all embodiments of thepresent invention. Different power supply configurations may, forexample, utilize disposable or removable batteries and eliminate theneed for internal charging means 424.

FIG. 5a illustrates operations for measuring and collecting vibrationdata from machines, implemented in a battery-operated powered computer.First, in Block 510 a user selects a machine identification formeasurement. In Block 520 a time domain accelerometer signal 515 isprocessed to produce a digital signal 525. In Block 530 the digitalsignal is analyzed to produce predictive maintenance information, suchas detection of alarm conditions due to vibration magnitudes exceedingpredetermined limits or reports concerning machine vibration parameters.Referring to FIG. 5b, in an alternate embodiment, the operations ofBlock 520 may be preceded by a step of sampling and digitizing an analogtime domain accelerometer signal to produce a time domain digitalaccelerometer signal 516, as shown in Block 511. In addition, predictivemaintenance information 526 may then be displayed, as shown in Block540.

Referring to FIG. 5c, the operations of block 511, of sampling anddigitizing an analog time domain accelerometer signal, to produce a timedomain digital accelerometer signal 516, may be performed using thedifferent data acquisition cards 120, such as the Magic Ram PCMCIA16-bit audio adapter identified above or the Bullet_(dsp) PCMCIA cardidentified above. Because data acquisition card 120 is removable, thecards may be exchanged for use in different measurements. Specifically,a first card may be used in block 545 for a first sampling operation anda second card may be used in block 550 for a second sampling operation.

Referring to FIG. 5d, the operations involved in trend analysis, asdiscussed above, are detailed. Specifically, in a first sample anddigitize step 511 a, analog time domain accelerometer signals areconverted to a digital time domain accelerometer signals. Similarly, ina second, later performance of a sample and digitize step 511 b, analogtime domain accelerometer signals collected at that time are convertedto a digital time domain accelerometer signals. Finally, signal analysis530, in the form of a trend analysis 530′, is performed, to identifychanges between the first and second stored digital signal created insteps 511 a and 511 b, respectively.

Referring to FIG. 5e, step 510 of FIG. 5a, of selecting a machineidentification, is detailed. A machine identification and associatedparameters are selected (510 a) in one of three ways. An identificationand associated previously stored parameters may be selected in step 510b. Alternatively, a machine identification and parameters may be enteredmanually in step 510 c (see FIG. 6b, below). As a further alternative,parameters may be entered with the aid of predetermined machinetemplates in step 510 d (see FIG. 6c, below).

FIGS. 6a-6 b illustrate the selection step of Block 510 of FIGS. 5a-5 bin greater detail. In FIG. 6a the user enters a data collection window600 in which he may select a machine identification for measurement, asshown at 601. The display informs the user of the identificationselected, which typically is a location on a particular machine, asshown at 602. The user typically commands data acquisition by selectionof an icon, as shown at 603.

The parameters associated with a particular machine identificationtypically have been previously entered into a database. This may be donemanually, as shown in FIG. 6b. Within a data entry window 610, the userselects a desired machine identification, as illustrated at 611, andenters the associated parameters, as shown at 612. Alternatively,parameters may be entered with the aid of predetermined machinetemplates, as shown in FIG. 6c. These parameters may include signalprocessing parameters for use in the processing step of Block 520 ofFIG. 5, but it will be understood by those skilled in art that otherarrangements may be used with the present invention, such as allowingthe user to select particular signal processing parameters while in datacollection window 600.

FIG. 7 illustrates the signal analyzing operation of Block 530 of FIG.5, specifically the displayed results of a spectrum analysis. It will beunderstood by those skilled in the art that other analyses may beperformed on digital signals, such as magnitude or crest factorcalculations or detection of alarm conditions.

FIG. 8 illustrates the data collection system of the present inventionfurther including transmission of machine identifications, measurementparameters, time domain accelerometer signals, frequency domain digitalsignals and predictive maintenance information to other computers 820a-820 n linked to the battery operated portable computer 110 by means ofa network 810. It will be understood by those skilled in the art thatnetwork 810 may be hardwired or may employ radio frequency (RF) or othercommunications links. Under this aspect of the invention,machine-related data may be uploaded from the battery powered portablecomputer 110 to computers 820 a-820 n for subsequent data management,processing, analysis or display.

In the drawings and specification, there have been disclosed typicalpreferred embodiments of the invention and, although specific terms areemployed, they are used in a generic and descriptive sense only and notfor purposes of limitation, the scope of the invention being set forthin the following claims.

That which is claimed:
 1. A method of collecting machinery maintenancedata from machines, comprising: providing a portable computer comprisinga processor, memory, battery, and external interface, providing ananalog machine activity sensor for collecting machinery maintenance datafrom one or more machines, during battery-powered operation of saidportable computer, collecting first data relating to operation of amachine at a first time, from said analog machine activity sensor, viasaid external interface, into said memory of said portable computer,during battery-powered operation of said portable computer, collectingsecond data relating to operation of said machine at a second timeseparate from said first time, from said analog machine activity sensor,via said external interface, into said memory of said portable computer,and retrieving said first and second data from said memory of saidportable computer to said processor of said portable computer and usingsaid processor to analyze said first and second data by comparing saidfirst and second data for changes indicative of machinery maintenanceneeds.
 2. The method of claim 1 wherein said memory comprises dynamicrandom access memory (DRAM).
 3. The method of claim 1 wherein saidmemory comprises magnetic storage.
 4. The method of claim 1 wherein saidmemory is removable.
 5. The method of claim 1 wherein said externalinterface is a card slot, and an interface card inserted therein, bothcompatible with a personal computer interface standard permittingremoval and replacement of said interface card without restartingoperation of said processor.
 6. The method of claim 5 wherein saidinterface card comprises an analog to digital converter.
 7. The methodof claim 1 wherein analyzing said first and second data comprisesoperating said processor to perform a frequency transformation of saidfirst and/or second data.
 8. The method of claim 1 further comprisingproviding a sensor power supply for supplying power to said analogmachine activity sensor.
 9. The method of claim 8 wherein said sensorpower supply is responsive to a control signal from said portablecomputer to activate or deactivate said analog machine activity sensor,and further comprising operating said portable computer to produce acontrol signal to activate said sensor power supply prior to collectingdata from said analog machine activity sensor.
 10. The method of claim 8further comprising providing an interface cord connecting said sensorpower supply and said analog machine activity sensor to said portablecomputer.
 11. The method of claim 8 wherein said sensor power supplycomprises a sensor power supply battery, and further comprisingproviding a battery charger and connecting said battery charger to saidsensor power supply battery to charge said sensor power supply battery.12. The method of claim 1 further comprising storing in said memorymachine identifications and associated measurement parameters for aplurality of machines.
 13. The method of claim 12 wherein said portablecomputer further comprises a connector for transmitting informationbetween said memory and a host computer.
 14. The method of claim 13further comprising transmitting at least one of data collected from saidanalog machine activity sensor, an identification of a machine, andmeasurement parameters between said memory and said host computer viasaid connector.
 15. The method of claim 12 wherein said portablecomputer further comprises a user interface, and further comprisinginteracting with said processor using said user interface to select amachine identification, and then processing data collected from saidanalog machine activity sensor in accordance with measurement parametersassociated with said selected machine identification.
 16. The method ofclaim 1 wherein said portable computer further comprises a display. 17.The method of claim 16 further comprising operating said processor todisplay data collected from said analog machine activity sensor on saiddisplay.
 18. The method of claim 16 further comprising operating saidprocessor to perform a frequency transformation of data collected fromsaid analog machine activity sensor and display said frequencytransformation on said display.
 19. The method of claim 1 wherein saidportable computer has less than a full set of alphanumeric keys.
 20. Themethod of claim 19 wherein said portable computer is a pen-based palmtopcomputer.
 21. The method of claim 1 wherein said analog machine activitysensor is an accelerometer.
 22. A computer system for collectingmachinery maintenance data from machines, comprising: a portablecomputer comprising a processor, memory, battery, external interface,and user interface, said user interface having less than a full set ofalphanumeric keys, software in said memory for operating said processorto collect first and second data relating to operation of a machine atfirst and second separated times, from an analog machine activity sensorconnected to said external interface, and store said first and seconddata into said memory of said portable computer, and software in saidmemory for operating said processor to retrieve said first and seconddata collected from said single machine from said memory of saidportable computer to said processor of said portable computer and usesaid processor to analyze said first and second data by comparing saidfirst and second data for changes indicative of machinery maintenanceneeds.
 23. The computer system of claim 22 wherein said memory comprisesdynamic random access memory (DRAM).
 24. The computer system of claim 22wherein said memory comprises magnetic storage.
 25. The computer systemof claim 22 wherein said memory is removable.
 26. The computer system ofclaim 22 wherein said external interface is a card slot, and aninterface card inserted therein, both compatible with a personalcomputer interface standard permitting removal and replacement of saidinterface card without restarting operation of said processor.
 27. Thecomputer system of claim 26 wherein said interface card comprises ananalog to digital converter.
 28. The computer system of claim 22 whereinsaid software operates said processor to perform a frequencytransformation of said first and/or second data.
 29. The computer systemof claim 22 further comprising a sensor power supply for supplying powerto said analog machine activity sensor.
 30. The computer system of claim29 wherein said sensor power supply is responsive to a control signalfrom said portable computer to activate or deactivate said analogmachine activity sensor, and further comprising software in said memoryfor operating said portable computer to produce a control signal toactivate said sensor power supply prior to collecting data from saidanalog machine activity sensor.
 31. The computer system of claim 29further comprising an interface cord connecting said sensor power supplyand said analog machine activity sensor to said portable computer. 32.The computer system of claim 29 wherein said sensor power supplycomprises a sensor power supply battery, and further comprising abattery charger connectable to said sensor power supply battery tocharge said sensor power supply battery.
 33. The computer system ofclaim 22 further comprising machine identifications and associatedmeasurement parameters for a plurality of machines stored in saidmemory.
 34. The computer system of claim 33 further comprising aconnector for transmitting information between said memory and a hostcomputer, including at least one of data collected from said analogmachine activity sensor, an identification of a machine, and measurementparameters.
 35. The computer system of claim 33 further comprisingsoftware in said memory for operating said processor to interact with auser to select a machine identification, and then process data collectedfrom said analog machine activity sensor in accordance with measurementparameters associated with said selected machine identification.
 36. Thecomputer system of claim 22 wherein said portable computer furthercomprises a display.
 37. The computer system of claim 36 furthercomprising software in said memory for operating said processor todisplay data collected from said analog machine activity sensor on saiddisplay.
 38. The computer system of claim 36 further comprising softwarein said memory for operating said processor to perform a frequencytransformation of data collected from said analog machine activitysensor and display said frequency transformation on said display. 39.The computer system of claim 22 wherein said portable computer is apen-based palmtop computer.
 40. A computer system for collectingmachinery maintenance data from machines, comprising: a portablecomputer comprising a processor, memory, battery, and externalinterface, an analog machine activity sensor for collecting machinerymaintenance data from one or more machines, software in said memory foroperating said processor, during battery-powered operation thereof, tocollect first and second data relating to operation of a machine atfirst and second separated times, from said analog machine activitysensor, via said external interface, and store said first and seconddata into said memory, software in said memory for operating saidprocessor to retrieve said first and second data from said memory tosaid processor and analyze said first and second data by comparing saidfirst and second data for changes indicative of machinery maintenanceneeds.
 41. The computer system of claim 40 wherein said memory comprisesdynamic random access memory (DRAM).
 42. The computer system of claim 40wherein said memory comprises magnetic storage.
 43. The computer systemof claim 40 wherein said memory is removable.
 44. The computer system ofclaim 40 wherein said external interface is a card slot, and aninterface card inserted therein, both compatible with a personalcomputer interface standard permitting removal and replacement of saidinterface card without restarting operation of said processor.
 45. Thecomputer system of claim 44 wherein said interface card comprises ananalog to digital converter.
 46. The computer system of claim 40 whereinsaid software further operates said processor to analyze said first andsecond data by operating said processor to perform a frequencytransformation of said first and/or second data.
 47. The computer systemof claim 40 further comprising a sensor power supply for supplying powerto said analog machine activity sensor.
 48. The computer system of claim47 wherein said sensor power supply is responsive to a control signalfrom said portable computer to activate or deactivate said analogmachine activity sensor, and wherein said portable computer comprisessoftware operating said processor to produce a control signal toactivate said sensor power supply prior to collecting data from saidanalog machine activity sensor.
 49. The computer system of claim 47further comprising an interface cord connecting said sensor power supplyand said analog machine activity sensor to said portable computer. 50.The computer system of claim 47 wherein said sensor power supplycomprises a sensor power supply battery, and further comprising abattery charger connectable to said sensor power supply battery tocharge said sensor power supply battery.
 51. The computer system ofclaim 40 wherein said memory stores machine identifications andassociated measurement parameters for a plurality of machines.
 52. Thecomputer system of claim 51 wherein said portable computer furthercomprises a connector for transmitting information between said memoryand a host computer.
 53. The computer system of claim 52 furthercomprising software operating said processor to transmit at least one ofdata collected from said analog machine activity sensor, anidentification of a machine, and measurement parameters between saidmemory and said host computer via said connector.
 54. The computersystem of claim 51 wherein said portable computer further comprises auser interface, and software operating said processor using said userinterface to select a machine identification, and then process datacollected from said analog machine activity sensor in accordance withmeasurement parameters associated with said selected machineidentification.
 55. The computer system of claim 40 wherein saidportable computer further comprises a display.
 56. The computer systemof claim 55 further comprising software operating said processor todisplay data collected from said analog machine activity sensor on saiddisplay.
 57. The computer system of claim 55 further comprising softwareoperating said processor to perform a frequency transformation of datacollected from said analog machine activity sensor and display saidfrequency transformation on said display.
 58. The computer system ofclaim 40 wherein said portable computer has less than a full set ofalphanumeric keys.
 59. The computer system of claim 58 wherein saidportable computer is a pen-based palmtop computer.
 60. The computersystem of claim 40 wherein said analog machine activity sensor is anaccelerometer.
 61. A method for collecting machinery maintenance datafrom machines, comprising: providing a portable computer comprising aprocessor, memory, battery, external interface, and user interface, saiduser interface having less than a full set of alphanumeric keys,operating said processor to collect first and second data relating tooperation of a machine at first and second separated times, from ananalog machine activity sensor connected to said external interface, andstore said first and second data into said memory of said portablecomputer, and operating said processor to retrieve said first and seconddata collected from said single machine from said memory of saidportable computer to said processor of said portable computer and usesaid processor to analyze said first and second data by comparing saidfirst and second data for changes indicative of machinery maintenanceneeds.
 62. The method of claim 61 wherein said memory comprises dynamicrandom access memory (DRAM).
 63. The method of claim 61 wherein saidmemory comprises magnetic storage.
 64. The method of claim 61 whereinsaid memory is removable.
 65. The method of claim 61 wherein saidexternal interface is a card slot, and an interface card insertedtherein, both compatible with a personal computer interface standardpermitting removal and replacement of said interlace card withoutrestarting operation of said processor.
 66. The method of claim 65wherein said interface card comprises an analog to digital converter.67. The method of claim 61 further comprising operating said processorto perform a frequency transformation of said first and/or second data.68. The method of claim 61 further comprising providing a sensor powersupply for supplying power to said analog machine activity sensor. 69.The method of claim 68 wherein said sensor power supply is responsive toa control signal from said portable computer to activate or deactivatesaid analog machine activity sensor, and further comprising operatingsaid portable computer to produce a control signal to activate saidsensor power supply prior to collecting data from said analog machineactivity sensor.
 70. The method of claim 68 further comprising providingan interface cord connecting said sensor power supply and said analogmachine activity sensor to said portable computer.
 71. The method ofclaim 68 wherein said sensor power supply comprises a sensor powersupply battery, and further comprising providing a battery chargerconnectable to said sensor power supply battery to charge said sensorpower supply battery.
 72. The method of claim 61 further comprisingstoring machine identifications and associated measurement parametersfor a plurality of machines in said memory.
 73. The method of claim 72further comprising transmitting information between said memory and ahost computer, including at least one of data collected from said analogmachine activity sensor, an identification of a machine, and measurementparameters.
 74. The method of claim 72 further comprising operating saidprocessor to interact with a user to select a machine identification,and then process data collected from said analog machine activity sensorin accordance with measurement parameters associated with said selectedmachine identification.
 75. The method of claim 61 wherein said portablecomputer further comprises a display.
 76. The method of claim 75 furthercomprising operating said processor to display data collected from saidanalog machine activity sensor on said display.
 77. The method of claim75 further comprising operating said processor to perform a frequencytransformation of data collected from said analog machine activitysensor and display said frequency transformation on said display. 78.The method of claim 61 wherein said portable computer is a pen-basedpalmtop computer.